Apple Inc. and the family of Steve Jobs were not saying what caused the death of the company’s founder. However, medical experts said that the liver transplant he had two years ago was probably a sign that his cancer had returned.

t’s well known that the secret to Apple Inc.’s meteoric success in the world of consumer technology was the vision, leadership and creativity of Steve Jobs. What’s less talked about is what drove Jobs, who died Wednesday at 56.

While Steve Jobs had no formal schooling in engineering, he pushed the envelope many times when it came to product design. He’s listed as the inventor or co-inventor on more than 300 U.S. patents, but other times the results of his work weren’t always pretty.